Water production is one of the major problems that occur in oil producer wells, which are at their most profitable when they are producing only oil. Produced water is an inevitable consequence of water injection when waterflooding is used to develop an oil reservoir or when the field drive mechanism involves strong aquifer support. Various problems are associated with the production of water including (a) the “lifting” (pumping) of the water itself from downhole to the surface, (b) the corrosion that may occur in downhole completions, tubulars, valves and surface equipment due to the corrosivity of the produced brine, (c) in some cases, mineral scale deposition due to the presence of precipitating minerals in the produced water (commonly calcite—calcium carbonate and barite—barium sulphate etc.), (d) the possible formation of gas hydrates (water/gas “ice”) at low temperatures in sub-sea lines, and (e) the treating of the water to remove any environmentally unfriendly substances (such as low levels of hydrocarbons) before disposal, etc. All of these problems result in expenditure of time, money and other resources and hence, are detrimental to the profitability of an oil production operation.
A chemical treatment that would reduce water production while preserving the flow of oil in an oil production well is known as a “water control” treatment (WCT). Many patents exist based on polymeric materials and their cross-linked gels, and also on other materials, describing how to perform such treatments. Likewise, certain downhole chemical treatments to inhibit the formation of mineral scale using chemical scale inhibitors are also well known and are referred to as “scale inhibitor ‘squeeze’ treatments” (SISTs). Again, many scale inhibitor chemicals and application processes are described in the scientific and patent literature.
As will be discussed in further detail, water control treatments and scale inhibitor treatments of subterranean formations involve a number of steps to achieve effective results. As will also be further explained, scale formation is partly a function of water production. Thus, it would be desirable if methods or techniques could be found which would combine these treatments so that the total number of steps could be minimized, yet achieve comparable results.